This application is based on and incorporates herein by reference Japanese Patent Application No. Hei. 11-355643 filed on Dec. 15, 1999.
1. Field of the Invention
The present invention relates to a valve timing adjuster used for controlling a valve timing of an intake valve or an exhaust valve of an internal combustion engine.
2. Description of Related Art
A vane type valve timing adjuster is used for controlling a valve timing of an intake valve or an exhaust valve of an engine.
The vane type valve timing adjuster includes a vane rotating with a camshaft. The vane is provided within a housing rotating with a timing pulley. A fluid pressure chamber is formed between the housing and the vane, and fluid pressure therein acts on the camshaft and the timing pulley to rotate relatively to each other. In this way, the valve timing adjuster controls the valve timing of the intake valve or the exhaust valve based on an engine driving condition.
JP-A-10-252420 and JP-A-11-132014 disclose a valve timing adjuster including a coil spring to urge a camshaft in an advance direction with respect to a housing. In JP-A-10-252420 and JP-A=11-132014, both ends of the coil spring are inserted into holes within a housing side member and a camshaft side member, respectively. The both ends of the coil spring are axially bent to fix to the housing side member and the camshaft side member.
The coil spring should be bent by particular bent radius over a predetermined radius for attaining a sufficient strength. Thus, when the coil spring is axially bent, there is a need to provide an axially large space for preventing the bent portion of the coil spring from contacting with the housing side member and the camshaft side member, thereby enlarging the entire valve timing adjuster in the axial direction.
An object of the present invention is to reduce a size of a vane type valve timing adjuster containing a coil spring.
According to a first aspect of the present invention, a coil spring urges a vane so that a following shaft advances or retards with respect to a driving shaft. The coil spring includes a first end fit to a housing, and a second end fit to the vane. At least one of the f first and second ends is radially bent for positioning the coil spring. Thus, the axial length of the housing containing the coil spring is shortened, thereby compacting the entire valve timing adjuster.
According to a second aspect of the present invention, the radially bent end of the coil spring is fit to a fixed member axially protruding from one of the housing and the vane. Thus, the coil spring easily positioned.